Over the years, enhancements have been made to rearview mirrors for vehicles by using lights in conjunction with such mirrors to provide a number of lighted auxiliary features. For example, rearview mirrors can incorporate lighted auxiliary features including, but not limited to, turn signals, blind spot detection displays (“BSDDs”), hazard warning lights, brake lights, or parking assist lights. Rearview mirror enhancements such as these have safety benefits, and are desirable to vehicle drivers for a variety of reasons. But there are a number of challenges to designing an optimal, efficient, and cost effective lighting assembly for such applications.
The challenges presented in this field generally relate to the small space constraints within the housing of the rearview mirror and the functionality of the mirror itself and the lighted auxiliary features. Specifically, lighting assemblies used for such features must be sized to fit behind the mirror, but within the mirror housing. The lighting assemblies must also be small and limit mirror vibration. A variety of light sources can be used, but light-emitting diodes (“LEDs”) are a common light source because they are small and generate large amounts of light, with lower energy consumption and heat generation, relative to their size. Any type of lights, however, generate heat and use energy. Thus, it is desirable to use as few lights or LEDs as possible to avoid excess heat and energy use. One additional aspect of designing lighted displays for rearview mirrors is that the visible light emitted from lighted auxiliary features should be sufficiently outside of or inside of the vehicle operator's line of sight during regular vehicle operation to avoid interfering with or to augment safe operation of the vehicle.
Early lighted auxiliary features for rearview mirrors were accomplished by using a simple “tilted LED” design, such as that disclosed in U.S. Pat. No. 6,257,746. In an embodiment of the tilted LED design, the lighting assembly is comprised of lights, such as LEDs, mounted on a substrate. The lights are positioned in an oblique orientation relative to the mirror, that is, they are “titled” away from the vehicle operator's line of sight and are not pointing directly through the mirror. The tilted LED design also uses a light diverting substrate which substantially prevents the lighting assembly from being visible when the lights are unlit. In this design, one LED or light is required for each aperture through which light passes out of the mirror. Although this design is still currently used, the lighting assembly in this design uses multiple LEDs and therefore a substantial amount of energy and also takes up a relatively substantial space.
As an alternative to the tilted LED design, optic assemblies have also been used to provide the lighting assembly for lighted auxiliary features in rearview mirrors. One early type of optic assembly is disclosed in U.S. Pat. No. 6,045,243, which is an example of the “Fresnel and deviator” design. The Fresnel and deviator optic design uses two or more optical elements to substantially converge and redirect light from light sources through the mirror in a way that does not interfere with the line of sight of the vehicle driver. In this design, the light emitting portion of the light source is either positioned facing the mirror or obliquely thereto. Light from the light source is first substantially collected and converged by a lens which may have refracting portions, reflective portions, or both. The collected light rays are then diverted by an optical element or elements (i.e., the “deviator”) by a certain amount, for example, 20-40 degrees from a line positioned normal to the front surface of the mirror, so that the light which is ultimately utilized by the lighted auxiliary feature and ultimately passed through the mirror does not interfere with the lines of sight of the vehicle operator. The Fresnel and deviator design may use a variety of different light sources, ranging from LEDs to light bulbs, but this design requires a relatively large amount of light and therefore uses a large amount of energy, emits a relatively large amount of heat and uses a relatively large amount of space.
Another type of optic assembly used is the “Paralocs” design that is disclosed in U.S. Pat. No. 6,076,948, and other patents. “Paralocs” is an abbreviation for Parabolic Array of LEDs on a Cut-Out Substrate. In the Paralocs design, the light sources used, typically LEDs, generally face away from the mirror, unlike the Fresnel and deviator design in which the light sources face the mirror. In the Paralocs design, light from the light source is substantially converged and directed at the same time with the use of a parabolic-shaped reflector. This design usually uses one reflector for each light source. Planar redirecting facets have also been used to increase efficiency and uniformity on Paralocs optics. This type of faceting redirects light that has already been significantly converged by another part of the optic. This allows the optic designer to use light from the far side of the LED, which would ordinarily be unused. However, the Paralocs design still requires one LED or light source per aperture through which light is emitted, and one reflector facet per LED or light source, and therefore still has some of the disadvantages of the earlier optical techniques.
Another type of optic used is referred to as a “Half Optic,” and is described in U.S. Pat. No. 7,273,307. An example of this type of optic uses a small reflector to direct and converge light from a light source through an aperture. The light source in the Half Optic design faces the mirror and is also positioned quite close to the mirror. This design has special utility when trying to direct light at angles very close to the mirror surface, but has some of the same disadvantages regarding the number of LEDs or light sources required, and permits less sophisticated control over the direction of the light rays through the aperture.
While the aforementioned designs provide ways to accomplish a number of lighted auxiliary features in rearview mirrors, the aspects of size, cost, and efficiency of the light assemblies used still have not been fully optimized. As such, there remains a need for a lighting assembly that will reduce the cost and size of lighted auxiliary features in rearview mirrors. The optic assembly for mirrors of the present invention addresses many of these problems. When utilizing the techniques described herein, the optic assembly of the present invention will allow using as little as one LED for lighted auxiliary displays that previously required 4 to 9 LEDs. It will also allow a significant reduction in assembly size, as well as a significant reduction in power consumption and generation of heat.
It will be understood by those skilled in the art that one or more aspects of this invention can meet certain objectives, while one or more other aspects can lead to certain other objectives. Other objects, features, benefits and advantages of the present invention will be apparent in this summary and descriptions of the disclosed embodiments, and will be readily apparent to those skilled in the art. Such objects, features, benefits and advantages will be apparent from the above as taken in conjunction with the accompanying figures and all reasonable inferences to be drawn therefrom.